This question appears to be off-topic. The users who voted to close gave this specific reason:

"Application/website recommendations are off-topic and out of scope. It is better instead to use a particular web app or website and ask for help in any issues you have with it specifically." – Al E., Vidar S. Ramdal, Sathya

This is the same technology behind the Facebook docs service, so I suspect they will be very similar in functionality, except this is tied to your Hotmail or Skydrive account instead of your Facebook account.

It's a free online text editor, which does not require registration and is much more feature rich than most other web based text editors, because it's written in Silverlight and does not have the limitations of HTML and JavaScript. The only drawback is that it requires the Silverlight plugin installed to your browser.